Not Applicable
Not Applicable
1. Field of the Invention
This invention pertains generally to precision farming implements and methods, and more particularly to an apparatus and method for determining, evaluating and analyzing soil profile force measurements using an instrumented tine.
2. Description of the Background Art
Efficient farm management has become even more important to the economic survival of farmers in recent years because of increases in capital investment, increases in operating costs, and growing environmental constraints. The impact of agricultural production on the environment from chemical runoff and soil erosion has lead to the adoption of conservation tillage and precision farming techniques by farmers. Proper use of conservation tillage and precision farming techniques may lead to a reduction of soil erosion, over-fertilization and excess watering as well as a reduction in energy input and production costs. Logically, greater profits may be achieved through increasing crop production or decreasing the costs of production.
The physical and chemical characteristics of the soil as well as environmental conditions are generally regarded as the main sources of variability in crop yield. Good plant growth is influenced by the exchange of air and water with plant roots. The structure of the soil affects the movement of plant roots, air and water through the soil and ultimately the productivity of the field. Stable groupings of particles of clay, sand, organic matter and silt form aggregates that provide a rough network of passages or channels that allow the free exchange of air and water with the roots of the plants. The stability of the soil structure may be influenced by the size and type of particles forming the aggregate, wetting and drying cycles, temperatures extremes, freezing and thawing, mechanical compaction and the presence of inorganic and organic cementing agents within the soil. Soil structure can also be adversely influenced by excessive cultivation and the tillage of wet soils.
The density and structure of the soil and the size and continuity of the spaces between particles comprising the soil determine the permeability of the soil to the movement of air and water. The ability of a soil to absorb irrigation water or rain over a specified period of time is dependent on the permeability of the surface soil, the moisture content of the soil and the slope of the field. Soils with very slow or very fast infiltration rates are generally considered to be poor soils for irrigation. In addition, a reduction of water infiltration and hydraulic conductivity within the soil profile due to soil compaction or crusting can contribute to runoff and erosion. Moreover, reduced infiltration rate and hydraulic conductivity leads to lower soil moisture status and poor yield.
In addition to adversely affecting the availability of soil moisture within the root zone, the possible serious, long-term effects of soil compaction on the quality of the environment has become a serious issue in recent years. Soil compaction may have a significant environmental effect in four general areas: atmosphere, surface water, ground water and soil vitality. Atmospheric effects of soil compaction are seen in the increased emission of greenhouse gases caused by anaerobic conditions present in moist and compact soils as well as emissions from machinery due to the need of increased tillage required for compact soils. Decreased infiltration in compact soils leads to increased runoff and the associated erosion and chemical runoff that may occur. Compacted soils result in reduced root growth and a decreased ability to absorb nutrients in a plant producing an increased need for fertilizer applications to maintain crop production. Ground water contamination by excessive fertilizer applications is a continuous environmental concern. Another adverse effect of soil compaction results in a reduction in the physical, chemical and biological quality of the soil such as decreased hydraulic conductivity and a loss of habitat for micro-fauna and macro-fauna in the soil.
Soil structure may deteriorate in many ways resulting from exposure to machinery traffic, a percentage decrease in the organic matter in the soil or through certain tillage practices. The severity of the compaction may vary depending on the soil type, crop type and soil moisture present in the field.
Soil compaction is typically monitored by the use of an ASAE (American Society of Agricultural Engineers) standard cone penetrometer providing a soil cone index value. Although cone index measurements provide variability in soil compaction through depth, they are point measurements that may be highly variable and may not be indicative of the conditions of the entire field.
In contrast, Texture/Compaction Index (TCI) sensor measures soil cutting force continuously over the entire tillage depth that provides a single measure of average soil compaction over the whole profile. However, this device can not provide variability in soil compaction level with depth which is critical for locating compact layers within the soil profile.
All of the aforementioned concerns point to the need for an analytical apparatus and method that can sense soil compaction status that will allow field management decisions including tillage depths and optimized soil particle sizes, crop selection, improve water infiltration characteristics, fertilization types and application rates and other precision farming decisions. Informed farming decisions and practices will reduce the input of energy and maximize the net return from the field. The present invention satisfies these needs, as well as others, as will be seen herein.
The present invention is directed to an agricultural soil profile sensor apparatus and method for providing field position relevant measurements of soil compaction and other soil characteristics with respect to soil depth in real-time.
In general terms, the invention comprises a plurality of cutting elements and means for measuring force on each of the cutting elements as said cutting elements are pulled through soil.
According to another aspect of the invention, the apparatus comprises a tine having a plurality of cutting elements, and a plurality of independent load cells supporting said cutting elements on said tine wherein the load cells are configured for measuring force on each of the cutting elements as said cutting elements are pulled through soil.
In accordance with a still further aspect of the invention, the apparatus comprises a tine having a plurality of cutting elements, means for measuring soil resistance to cutting as said cutting elements are pulled through soil, and means for mapping the variability in soil resistance to cutting with respect to depth.
The invention also includes a method for measuring variability in soil compaction with respect to depth that generally comprises measuring soil resistance to cutting as a plurality of cutting elements are pulled through soil.
By way of example, and not of limitation, a profile sensor apparatus according to the present invention generally comprises a tine that is drawn vertically through the soil at depths of up to approximately 60 centimeters that provides a platform for a variety of sensors.
It has been shown that the physical and chemical characteristics of the soil as well as environmental conditions are generally the main causes of variability in crop yields. One of the most important soil characteristics is the variability in soil moisture status. Soil moisture variability is governed by poor soil infiltration characteristics which in turn are associated with an increased level of soil compaction and/or changes in soil texture. It will be seen that the cutting force exerted on the apparatus as it is pulled through soil is influenced by soil moisture content, depth of operation of the tine and the vertical location of the cutting element.
According to an aspect of the invention, the tine has a plurality of independent cutting elements that are configured to transfer forces onto load cells. Each edge provides cutting resistance information over, for example, a 7.5-centimeter layer in the soil profile to a total depth, for example, of 60 centimeters. Each layer has a 5 cm cutting element separated by a 2.5 cm dummy element. Each cutting element is preferably coupled to a load cell or other device for measuring force. The dummy elements serve to allow discrete layer measurements.
The tine may also have other sensors located above or below ground. For example, temperature sensors, depth sensors, moisture sensors, salinity sensors and field position sensors and the like may be used to provide additional data for a field profile over a growing season or in the short term. Additional sensors may also be located on the vehicle.
In use, the apparatus is drawn linearly through the subject field, and measurements of the mechanical impedance through different layers within the soil profile are preferably taken. In one embodiment, the soil force measurements are recorded by a data logger and stored for analysis away from the field. In another embodiment, the force measurements are stored and analyzed by a computer and the results displayed in real time. In another embodiment, the computer stores and compares previous measurements and data with the current measurements to disclose trends and improvements.
A map of the field at various depths may also be created from the obtained data and correlated surface positions within the field in one embodiment. Decisions regarding irrigation frequencies, fertilizer application, mulching, crop rotation, tilling practices and the like can be made from the derived map and field profile.
An object of the invention is to provide an apparatus and method that will provide real-time soil compaction profiles for an entire field.
Another object of the invention is to provide a soil profile monitoring device that is accurate, easy to use, provides a visual display of obtained profile data that is easy to understand and is relatively inexpensive to manufacture.
Another object of the invention is to provide a soil compaction map with respect to soil depth and field position.
Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon.